Inorg. Chem. 1989, 28, 692-696
692
4-Me-L-2,2,2, 4,7-Me2-L-2,2,2, 4-Et-L-2,2,2, and 4-Me-L-2,3,2, respectively, in the presence and absence of Cu2+at 25.0 f 0.1 OC and p = 0.10 M (NaCIO,), Figures 5S-8S, showing the results of Job's method of isomolar solutions of copper(I1) and (4-Me-L-2,2,2), copper(I1) and (4,7-Me-L-2,2,2), copper(I1) and (4-Et-L-2,2,2), and copper(I1) and (4-Me-L-2,3,2), respectively, at 25.0 f 0.1 OC and p = 0.10 M (NaCIO,), Figures 9s-1 IS, showing the electronic absorption spectra of copper(I1) and (4-Me-L-2,2,2), copper(I1) and (4-Et-L-2,2,2), and copper(I1) and (4-Me-L-2,3,2) solutions, respectively, Figures 12S-l5S, showing the degree of formation of copper (11)-(4,7-Me2-L-2,2,2), copper(II)-(4-Me-L-2,3,2), copper(II)-(4-Et-L-2,2,2),and copper(I1)-(4Me-L-2,3,2) complexes, respectively, in 1: 1 metal-ligand solution, Figures 16S-l8S, showing the observed first-order rate constants (/cobs) as a function of [Cu2'] for the formation of [Cu(4,7-Me2-L-2.2,2)J2+,
[Cu(4-Me-L-2,2,2)Izt, and [Cu(4-Et-L-2,2,2)I2', respectively, at 25.0 f 0.1 OC and p = 0.1 M (NaClO,), Figures 19s-21.3, showing the
resolution of the formation rate constants for copper(I1) reacting with unprotonated and monoprotonated 4-Me-L-2,2,2, 4-Et-L-2,2,2, and 4,7Me2-L-2,2,2, respectively, at 25.0 f 0.1 OC and = 0.10 M (NaCIO,), Figure 22.3, showing the observed rate constants (kobs)as a function of [Cuzt] for the formation of [Cu(4-Me-L-2,3,2)I2' at 25.0 f 0.1 OC and p = 0.10 M (NaCIO,), Figure 23S, showing the resolution of the formation rate constants for copper(I1) reacting with unprotonated and monoprotonated 4-Me-L-2,3,2 at 25.0 f 0.1 OC and p = 0.10 M (NaCIO,), and Figure 24S, showing the resolution of the dissociation rate constants involving proton-independent and proton-dependent terms for [Cu(4-Me-L-2,3,2)I2+at 25.0 f 0.1 OC and p = 0.10 M (NaC10,) (34 pages). Ordering information is given on any current masthead page.
Contribution from the Department of Chemistry, The University, Southampton SO9 5NH, England
Chelating Ditelluroether Complexes of Palladium and Platinum: Synthesis and Multinuclear NMR Studies. Structure of Dibromo(meso - 1,3-bis(phenyltelluro)propane)palladium(11), [Pd(meso-PhTe(CH2)3TePh)Brz] Tim Kemmitt, William Levason,* and Michael Webster Received July 12, 1988 Palladium(I1) and platinum(I1) complexes of two chelating ditelluroether ligands [M(L-L)X2](M = Pd or Pt, X = CI, Br, or I, and L-L = PhTe(CH2),TePh or MeTe(CH2),TeMe) are described. The complexes have been characterized by analysis and IR, UV-visible and multinuclear NMR (IH, IzsTe('H},195Pt(lHJ) spectroscopy. The NMR studies show that two diastereoisomers of the ligand are present in solution in each complex, meso and dl invertomers, with the former having the higher abundance. The structure of [Pd(meso-PhTe(CH2),TePh)Br2] has been determined by X-ray diffraction. Crystals belong to the triclinic crystal system, space group Pi,with a = 8.968 (1) A, b = 10.978 (1) A, c = 11.070 (2) A, a = 108.16 (1)O,@= 113.15 (1)O, y = 98.95 (1)O, and Z = 2. The structure was refined to an R value of 0.023 from 2545 reflections (F > 30(F)). The trends in the '25Te and lgsPt NMR chemical shifts and 1J('95Pt-'25Te)coupling constants are reported and discussed and are compared with data on the corresponding diselenoether complexes. Close parallels exist between 125Teand "Se chemical shifts in comparable complexes. Attempts to halogen oxidize the complexes to the M(IV) state have failed.
Introduction The coordination chemistry of organotellurium ligands is mainly limited to complexes of RTe-, R2Te, and R2Te2.' All attempts to prepare 1,2-di-R-telluroethanes have failed,2,3but we have recently reported3 that 1,3-di-R-telluropropanes,RTe(CH2)3TeR (R = M e or Ph), can be made in high yield from RTeLi and C1(CH2)3CI a t low temperatures. Here we report the synthesis and properties of palladium and platinum complexes of these two ligands and their IH, IZ5Te(lH),and 195Pt(1HJ NMR spectra. The work is an extension of our previous studies of diselenoether c ~ m p l e x e swith ~ * ~which detailed comparisons are drawn.
Results and Discussion The reaction of MeTe(CH2)3TeMe or PhTe(CHJ3TePh with the appropriate [M(MeCN)2X2](M = P d or Pt, X = C1, Br or I ) in CH2C12or M e C N gave [M(RTe(CH2),TeR)X2Jcomplexes (Table I). There is no evidence for the formation of [M(RTe(CH2)3TeR)2]2+ions even with a large excess of ligand. The solid complexes are air-stable in contrast to the air-sensitivity of the free ligands3 and are poorly soluble in chlorocarbons and M e C N For a recent excellent review see: Gysling, H. J.; In The Chemistry of Organic Selenium and Tellurium Compounds;Patai, S.;Rappoport, Z., Eds.; Wiley: New York, 1986; vol. 1, pp 679-855. Pathirana, H. M. K. K.; McWhinnie, W. R. J . Chem. SOC.Dalton Trans. 1986, 2003. Hope, E. G.; Kemmitt, T.; Levason, W. Organometallics 1987, 6, 206; 1988, 7, 78.
Gulliver, D. J.; Hope, E. G.; Levason, W.; Murray, S. G.; Marshall, G. L. J . Chem. SOC.,Dalton Trans. 1985, 1265. Hope, E. G.; Levason, W.;Webster, M.; Murray, S.G. J . Chem. SOC., Dalton Trans. 1986. 1003.
0020- 1669/89/ 1328-0692$01 S O / O
to give stable solutions. T h e complexes a r e more soluble in dimethyl sulfoxide ( D M S O ) and in N,N-dimethylformamide (DMF); however, decomposition is often apparent in DMSO over time. T h e physical data (Table I) are consistent with the formulation of all twelve complexes as cis planar materials, and this is confirmed by comparison with the data for the thio-6 and selenoether4 analogues, and by the X-ray study of [Pd(PhTe(CH2)3TePh)Br2J(below). Chelating bidentate group 16 donor ligand complexes exist in two isomeric forms, containing meso and dl geometries (Figure l), and these interconvert by pyramidal inversion a t the heteroatoms.' Structure of [P~(PIIT~(CH~)~T~P~)B~~]. T h e structure in the solid state consists of discrete molecules and is shown in Figure 2. The expected square-planar geometry around the Pd is found, and the principal feature of interest is the stereochemistry of the chelating ditellurium ligand. Inspection of the crystallographic literature* shows few examples of the monodentate T e ligands R2Te and apparently no examples of chelating ditellurium ligands although one example of a PTe donor ligand is known.9 T h e Pd-Te distances in the present compound (2.528,2.525 A) (Table 11) may be compared with 2.606 (1) 8,in t r u r ~ s - P d ( S C N ) ~ ( T e R ~ ) ~ ( R = Me3Si(CH2)2)10and the Pd-Br distance (2.480 (1) A) with 2.456 ( l ) , 2.468 (1) A in cis-PdBr2(C6H12S3)"and 2.431 (1) A (6) Hartley, F.R.; Murray, S. G.; Levason, W.; Soutter, H. E.; McAuliffe, C. A. Inorg. Chim. Acta 1979, 35, 265. (7) For a review see: Abel, E. W.; Orrell, K. G.; Bhargava, S. K. Prog. Inorg. Chem. 1984, 32, 1.
(8) Cambridge Structural Database, University Chemical Laboratory, Cambridge, England. (9) Gysling, H. J.; Luss, H. R. Organometallics 1984, 3, 596. (10) Gysling, H. J.; Luss, H. R.; Smith, D. L. Inorg. Chem. 1979, 18, 2696. 0 1989 American Chemical Society
Chelating Ditelluroether Complexes
Inorganic Chemistry, Vol. 28, No. 4, 1989 693
Table I. Selected Phvsical Data
complex [Pd(MeTe(CH2),TeMe)CI2] [ Pd(MeTe(CH2),TeMe}Br2] [Pd(MeTe(CH2),TeMe}12] [ Pd(PhTe( CH2),TePhlCl2] [Pd(PhTe(CH,),TePhlBr,] [Pd(PhTe(CH2),TePh}12] [Pt(MeTe(CH2),TeMe)CI2] [Pt(MeTe(CH2),TeMeJBr2] [Pt(MeTe(CH2),TeMe}12] [Pt(PhTe(CH2),TePh}CI2]
color vellow brange red yellow orange red pale yellow yellow orange pale yellow
[Pt(PhTe(CH2),TePh}Br2] yellow orange [ Pt(PhTe(CH,),TePh}I,]
Emx/1O3 cm-I (cmOl/dm3 mol-l cm-I)' 25.97 (3460)* 25.13 (4380)* 21.98 (4370), 30.58 (14440)* 25.38 (13 520) 24.57 (10040) 21.46 (3380), 28.17 (sh) (9720) 26.67 (sh) (424), 30.86 (sh) (1680)* 25.64 (450), 30.12 (sh) (2680)b 26.46 (2970), 30.77 (sh) (4170)b 24.39 (sh) (300), 29.41 (sh) (1520), 34.48 (5270) 25.64 (sh) (400), 33.33 (sh) (4430) 25.97 (4160)
v(M-X)/cm-IC % Cd 288 (br) 11.9 (12.2) 230 10.1 (10.3) 8.7 (8.5) 305, 290 28.6 (28.8) 220 25.1 (25.0) 22.1 (22.0) 301, 287 10.1 (9.9) 218 8.8 (9.0) 7.7 (7.6) 305, 290 25.1 (24.9) 224
WH)/ppmC meso dl 2.4 (2.5) 2.25 2.21 2.0 (2.1) 2.28 2.21 f 1.7 (1.8) 2.45 2.5 (2.5) 2.2 (2.1) 2.0 (2.1) 2.0 (2.0) 2.22 (32) 2.19 v) 1.8 (1.9) 2.32 (34) 2.30 (32) 1.5 (1.6) 2.42 (33) f 2.2 (2.3) % Hd
22.3 (22.4) 2.0 (2.0) 20.0 (20.1) 1.8 (1.9)
'In dimethyl sulfoxide solution. *In N,N-dimethylformamide solution. 'Nujol mulls. dCalculated values in parentheses. only, with 3J(195Pt-1H)(in Hz) in parentheses. fResonance of minor invertomer not clearly identified. (A) and [Pd(PhTe(CH2)pTePh)Br2] Pd-Br( 1) 2.480 (1) Pd-Br (2) 2.480 (1) Pd-Te(1) 2.528 (1) Pd-Te(2) 2.525 (1)
Table 11. Bond Distances
me so
^.
UL
C(7)-C(8) C(8)-C(9) C-H(fixed)
Figure 1. Structures of meso and dl invertomers.
Br(1)-Pd-Br(2) Br(l)-Pd-Te(2) Br(2)-Pd-Te(1) Te(1)-Pd-Te(2) Pd-Te(l)-C(9) Pd-Te(1)-C(10) C(9)-Te(l)-C(lO)
C(12)
View of discrete molecule showing the atom-numbering scheme. Thermal ellipsoids were drawn with 40% probability boundary surfaces and with hydrogen atoms omitted for clarity.
Figure 2.
in ~ ~ U ~ S - P ~ B ~ ~ ( C T h~e H ligand ~ N forms S ) ~ a. six-membered ~ ~ chelate ring in which five atoms are approximately coplanar with the sixth (C(8)) out of the plane by 0.73 A-the "sofa" conformation. The two phenyl rings lie on the same side of the chelate ring (and on the same side as C(8)) and this gives rise to the syn conformation (meso invertomer). Although this chelating ditellurium ligand is unique, five-membered rings with Pd and S2 ligands13 and Pt with S214J5 and Se25J6ligands are known and give rise to in some cases the syn (meso) conformation and in other cases the anti (dl) conformation in the solid state. NMR Studies. Little data are available on pyramidal inversion in coordinated telluroethers, but from studies on trans- [M(1 I ) Wieghardt, K.; Kiippers, H.-J.; Raabe, E.; Kriiger, C. Angew. Chem., Inz. Ed. Engl. 1986, 25, 1101. (12) Giordano, T. J.; Butler, W. M.; Rasmussen, P. G. Inorg. Chem. 1978,
.---
17. 1917.-
Pin-Xi, S.; Xinkan, Y . ; Yi-Xing, G. Acta Chim. Sin. 1984, 42, 20. Hunter, W. N.; Muir, K. W.; Sharp, D. W. A. Acta Crystallogr. 1986, 42C, 961. (15) Cano, 0.;Leal, J.; Quintana, P.; Torrens, H. Inorg. Chim. Acta 1984, 89, L9. (16) Abel, E. W.; Bhargava, S.K.; Orrell, K. G.; Platt, A. W. G.; Sik, V.; Cameron, T. S. J . Chem. SOC.,Dalton Trans. 1985, 345. (13) (14)
1.500 (6) 1.528 (6) 0.95 93.8 (1) 82.9 (1) 83.9 (1) 99.4 (1) 111.0 (1) 99.9 (1) 93.6 (2)
Methyl resonances
Angles (deg) for Te(1)-C(9) Te(1)-C(I0) Te(2)-C(l) Te(2)-C(7) Br(l)-.Br(2) Br(l).-Te(2) Br(2).-Te( 1) Te( 1)-.Te(2)
2.147 (4) 2.129 (4) 2.126 (4) 2.153 ( 5 ) 3.621 (2) 3.313 (2) 3.348 (2) 3.855 (2)
Te(2)-C(7)-C(8) C(7)-C(8)-C(9) C(8)-C(9)-Te(l)
121.0 (3) 114.7 (4) 117.5 (3)
Pd-Te(Z)-C(l) Pd-Te(2)-C(7) C(I)-Te(2)-C(7)
100.5 (1) 113.4 (1) 95.2 (2)
(ER2)2X2]17it appears that the barriers to inversion are in the order S < S e < Te. T h e 6(Me) resonances in the proton NMR spectra of [Pd(MeTe(CH2)3TeMe)X2]showed no evidence of broadening or coalescence over the temperature range 298-353 K in DMSO solution, although the solutions darkened probably due to some decomposition. It seems likely that the barrier energies to inversion in these compounds are too high to study by V T N M R methods, and NMR studies were limited to establishing trends in the static data (at 298 K) and to a comparison with data on the diselenoether analogues. The lH NMR data are given in data in Table 111, and the Table I, the lZ5Te('HJand 77Se(1H} 195Pt(lH) in Table IV. It is convenient to discuss each nucleus in turn. IH NMR. The [M(MeTe(CH2)3TeMe)Xz]( X = CI or Br) complexes show two methyl resonances, in the case of M = P t with satellites due to coupling to Ig5Pt. T h e major resonance to high frequency is identified as that due to the meso invertomer by comparison with the data on dithio-'* and d i ~ e l e n o e t h e r ~ analogues. T h e structure of the [Pd(PhTe(CH2)3TePh)Br2]also supports the isomer identification. Correlation of solid structure with the major solution form is generally open to considerable doubt and in some areas, e.g. isopolyanions, is notorious for the erroneous conclusions drawn in the older literature. However in cases like the present involving two diastereoisomers, it appears a more reasonable approach. Three X-ray studies-[Re(C0),1(me~o-MeSe(CH,)~SeMe]] l 9 a n d [PtMe,X(mesoMeSeCH=CHSeMeJ] (X = C1 or I)I6-have found that the (17) Cross, R. J.; Green,T. H.; Kat, R. J. Chem. SOC.,Dalton Trans. 1976, 1150. Cross, R. J.; Green, T. H.; Keat, R.; Paterson, J. J. Chem. SOC., Dalton Trans. 1976, 1486. (18) Abel, E. W.; Bhargava, S. K.; Kite, K.; Orrell, K. G.; Sik, V.; Williams, B. L. Polyhedron 1982, 1 , 289. (19) Abel, E. W.; Bhargava, S. K.; Bhatti, M. M.; Kite, K.; Mazid, M. A.; Orrell, K. G.; Sik, V.; Williams, B. L.; Hursthouse, M. B.; Malik, K. M. A. J . Chem. SOC.,Dalton Trans. 1982, 2065.
694 Inorganic Chemistry, Vol. 28, No. 4, 1989 Table 111. 125Te{1HJ and 77Se(lH)NMR Chemical Shift Data'sb complex meso 421 [Pd(MeTe(CH2)3TeMe)C12]C 399 [Pd(MeTe(CH2),TeMe}Br2]' 320 [Pd(MeTe(CH2)3TeMeJ12]c 588 [Pd[PhTe(CH2),TePh}CI2]f [Pd{PhTe(CH2),TePhJBr2l/ 564 512 [ Pd(PhTe(CH2),TePhl121/ [Pt(MeTe(CH2)3TeMe)C12]c 376 (1140) 361 (826) [Pt(MeTe(CH2),TeMe)Br21C 314 (257) [Pt(MeTe(CH2)3TeMe)12]C 566 (1600) [Pt(PhTe(CH2),TePhJCI2]' 559 (1240) [Pt(PhTe(CH2),TePhJBr,lc 525 (615) [Pt(PhTe(CH2)3TePh)12]f 178 (500) [Pt(MeSe(CH2),SeMe}CI2]f [Pt(MeSe(CH2),SeMe)Br2]f 171.5 (441) [Pt(MeSe(CH2),SeMe)121/ 163 (230) 314 (625) [Pt(PhSe(CH2)3SePhJC12]c 307 (300) [Pt(PhSe(CH2),SePhJBr2]e 303.5 (300) [Pt(PhSe(CH2)3SePhJ12]c
Kemmitt et al.
dl 340 319 26 1 556 531 477 313 (820) 307 (680) 275 (113) 540 (1200) 529 (970) 499 (415) 163 (518) 163 (400) 152 (180) 309 (576) 303 (480) 301.5 (295)
A(Te:Se)d 319,238 297,217 218, 159 132, 100 108,75 56, 21 274,211 257,204 212, 173 110,84 103,73 69, 43 112,97 105,97 97, 86 33, 28 26, 22 22, 20
meso:dP -1O:l
-1O:l -15:l -1O:l -1O:l -15:l
--
-1O:l
20:1 20:1 -5:l
-
-1O:l
20:1 -3:l -3:l -3:l -3:l -2:l -2:l
Relative to external neat TeMe2 or SeMe2 (6 = 0). 1J(lg5Pt-1ZSTe) or 1J(19SPt-77Se) coupling constants in parentheses (Hz). CApproximate isomer population. dCoordination shift (b(comp1ex) - 6(free ligand)). Free ligand shifts: MeTe(CH2),TeMe in DMF = 102 ppm, PhTe(CH,),TePh in DMSO = 456 ppm, PhSe(CH2),SePh in DMF = 281 ppm, and MeSe(CH2),SeMein DMSO = 64 ppm. CN,N-Dimethylformamidesolution. 'Dimethyl sulfoxide solution. Table IV. 195Pt('HJ NMR Chemical Shift Data' comulex meso [Pt(MeS(CH2)3SMeJC12]b -3570 [Pt(MeS(CH2),SMe}Br2] * -3922 [Pt{MeS(CH2),SMe)12] -4706 [Pt{PhS(CH2)$Ph)C12] -3584 [Pt(PhS(CH2),SPh)Br2] -3976 [ Pt{PhS(CH2)3SPh)IZ] -4805 [Pt{MeSe(CH2)3SeMe}C12]c -37 15 [Pt{MeSe(CH2),SeMe}Br2]c -4165 [Pt(MeSe(CHz),SeMe}I2] -4933 [Pt{PhSe(CH2),SePh]C12] -3720 [Pt(PhSe(CH2),SePh)Br2] -4175 [Pt(PhSe(CH2),SePhJ12] -5056 [Pt(MeTe(CH2),TeMeJCI2] -4434 [Pt(MeTe(CH2),TeMe]Br2] -4846 [Pt(MeTe(CH2),TeMe)12] -5639 [PtlPhTe(CH2),TePh}C12] -4406 [ Pt(PhTe(CH2),TePhJBr2] -4845 [ Pt(PhTe(CHz),TePh}I2] * -5696
dl -3538 -3893 -4680 -3544 -3948 -3662 -4121 -4901 -37 19 -4170 -5030 -4379 -4809 -5622 -4387 -4825 -5672
'6 relative to external 1 mol dm-' [PtC1J2- in H 2 0 ( = 0) in N, dimethylformamide solution except comuounds denote1 with footnote b. bDimethyl sulfoxide solution.' cVal& reported in ref 4 are erroneous.
geometry in the crystal corresponds to that of the major invertomer in solution. For [ M(MeTe(CH2)3TeMe]12]only one resonance in each was certainly identified, which is assigned to the meso invertomer. The 195Ptand IZ5TeN M R data below show that the abundance of the second isomer is very low, and in the proton spectra it could not be clearly identified since ligand backbone signals appear in the same region. The &(Me)resonances show the usual high frequency shift with trans ligand,4 C1 C Br < I, and for the platinum complexes 3J(195Pt-1H)is ca. 33 H z (Table
1).
Ig5Pt(lH)NMR. The platinum NMR spectra reveal two resonances with IZ5Tesatellites, of very disparate intensity for each complex. A typical example is shown in Figure 3. The more intense resonance (meso invertomer) has the more negative chemical shift, the differences between the two invertomers ranging from 20 to 55 ppm. There is very little literature data on Is5Pt spectra of tellurium complexes.20~21The data in Table IV show that there is a low-frequency shift with halogen, C1> Br > I, which is also observed with dithio- and diselenoether complexes. Within each type, replacement of C1 by Br results in a shielding of ca. 400 ppm, and replacement of Br by I results in a further shielding (20) Mason, J., Ed. Multinuclear NMR; Plenum: New York, 1987. (21) Pregosin, P. S. Coord. Chem. Reu. 1982, 44, 247.
11
-
1238 Hz
PPR
Figure 3. IgsPt[lH)NMR spectrum of [Pt(PhTe(CH2),TePh}Br2] in DMF (40 X lo3 transients; 298 K). of ca. 800 ppm. Changes in the terminal groups on the bidentate ligand (Me for Ph) have only small effects on 6(R),but changing the donor from S to S e to Te produces systematic low-frequency shifts. For constant X, replacement of dithio- by diseleno-ether produces a shift of ca -200 ppm, and diseleno- by ditelluro-ether has a larger effect ca -700 ppm. The effect on the 6(R)as group 16 is descended is consistent with the order of shifts with halide Cl > Br > I. 12STe(1H] NMR. Tellurium- 125 is a nucleus of only moderate 7%, D p = 2.21 X 10-3),20and this N M R sensitivity ( I = combined with the poor solubility of the complexes resulted in long accumulations being required (typically (250-350) X lo3 transients). A typical spectrum is shown in Figure 4. Even then the low abundance of the minor invertomer (dl) made it difficult to measure the 'J(19sPt-1ZSTe)couplings accurately for this form, and the data in Table I11 should be viewed in that light. The Iz5Te chemical shifts of the free ligands are known to be temperature, concentration, and solvent dependent.3*22For the complexes the 125Techemical shift varied by a few ppm ( Br > I and with the palladium complexes (22) Luthra, N. P.; Mom, J. D.In The Chemistry of Organic Selenium and Tellurium Compounds; Patai, S . , Rappoport, Z., Eds.; Wiley: New York, 1986, Vol. 1, pp 189-241.
Inorganic Chemistry, Vol. 28, No. 4, 1989 695
Chelating Ditelluroether Complexes
for [Pt(MezTe)Br3]-, and -400 H z for [Pt(Me2Te)13]-.2S It is now possible to compare corresponding dithioether, diselenoether, and ditelluroether complexes. Particularly notable is the invertomer ratio. In five-membered chelate ring complexes, [M(L-L)X,] (L-L = R E C H z C H 2 E R and E = S or Se), the dl invertomer is most a b ~ n d a n t although ,~ the d l m e s o ratio is not particularly disparate (14:1). For the six-membered rings, data appear to be available only for one dithioether [Pt(MeS(CHz)3SMelC12],I8 where the invertomers are of approximately equal abundance. For [Pt(RSe(CH2),SeR)X2] (Table 111) the meso form predominates, and in complexes of the two ditelluroethers the meso:dl ratio ranges from 5: 1 to ca. 20: 1. In complexes of six-coordinate platinum, e.g. [PtMe,X(L-L)] the meso:dl ratios are influenced by steric interactions with the axial ligands,I6 but this effect is necessarily absent in planar complexes. In the latter it seems likely that the major influence is strain within the ring as the ring size and donor atoms change, although the dependence of the meso:dl ratio upon the trans halide shows that electronic effects also influence the invertomer population. 590 580 570 560 550 540 530 520 SI0 500 400 480 M ~ F a r l a n eshowed ~~ in an early study that for comparable PPI organocompounds the 6(Te) and S(Se) resonances had an effecFigure 4. Iz5Te('HJNMR spectrum of [Pt(PhTe(CH2)3TePh)Br2]in tively constant ratio of ca. 1.8 (although theoretical explanation DMF (350 X IO3 transients; 298 K). of the value has proved elusive20). The present work allows similar comparison in S e and Te donor ligand complexes. We find that having larger shifts than the platinum analogues. The different comparison of the data in Table 111 for fixed M, X, and inverinvertomers have 6(Te) values that differ by 180 ppm, and the tomer, shows the S(Te):S(Se) ratio ranges from 2.1 1 to 1.66 with lzsTe spectra are particularly convenient for studying the inveran average of 1.8 (6). In view of the very different electronic tomers (cf. ref 4, 23). The meso invertomer has the higher environment in the complexes and the conformational limitations frequency resonance. Comparison of the coordination shifts (Table imposed by chelation, the appearance of the same approximate 111) reveals these to be greater for the MeTe(CH2)3TeMe comratio is remarkable and suggests that it may be similarly useful plexes than for those of PhTe(CH2),TePh. These trends are predictively. paralleled by the corresponding 77Se data on RSe(CH,),SeR Attempted Oxidation. We have described elsewhere the halogen (Table III), although in five-membered chelate rings (RSe(C12 or Brz) oxidation of platinum(I1) dithioether30 and di(CH2)2SeR complexes) the dl isomer has the more positive shift selenoether5 complexes to stable Pt(1V) analogues [Pt(L-L)X4]. and the halogen dependence is reversed (C1 C Br C I).4 As yet In contrast, the Pd(I1) complexes do not oxidize and the only no data for five-membered-ring ditelluroether complexes are examples of Pd(IV) complexes with neutral group 16 donor ligands available to complete the pattern, and in its absence the existence are the unstable [Pd(Me2E)XJ ions (E = S or Se; X = C1 or of a characteristic ring contribution to 6(Te), which is present in Br).5931 However the palladium(I1) or platinum(I1) ditelluroether 77Seand 31Pdata on diselenoether and diphosphine c o m p l e x e ~ , ~ . ~ ~ complexes were recovered unchanged after stirring with stoiis unclear. chiometric amounts of halogen in CCl,. Under more forcing Table I11 also lists 77Sedata on complexes of MeSe(CH,),SeMe conditions, i.e. a large excess of chlorine for several hours, [Ptand PhSe(CH2),SePh. The complexes of the latter decompose (PhTe(CH2),TePh)C12]was converted into a darker material of immediately in DMSO with liberation of free ligand: but in D M F variable composition. The far-IR spectra of these products showed solution with added [Cr(acac),] as a relaxation agent, data could v(Pt-Cl) stretches of the starting material and a new band a t ca. be acquired in about 4 h (typically 40 X lo3 transients), during 340 cm-' which suggests the presence of [PtC16]2-.32 Removal which about 10-20% decomposition occured. of the CCl, from one solution and dissolution of the product in The IJ('95Pt-12STe)coupling constants are listed in Table 111. D M F gave an orange solution with weak 6(lZSTe)N M R resoThe signs are undetermined, but by comparison with [Ptnances of the Pt(I1) starting material and a strong resonance at (Me2Te)X3]-25are probably negative. The magnitudes of IJ970 ppm. The white PhClzTe(CH2),TePhC12 (from the ligand (195Pt-12STe)decreased in the order C1 > Br > I, reflecting the C12) had 6(125Te)= 965 ppm in D M F , which in view of the usual dependence upon the trans influence of the trans halide,21 concentration sensitivity of organotellurium chemical shifts may as observed in IJ(19SPt-77Se)and IJ('9sPt-3'P) in selenoether and be taken as good agreement. Hence we conclude that stable tertiary phosphine c ~ m p l e x e s . ~ *The ~ ' ~effect ~ ~ ~of~ invertomer ~ Pt(1V) complexes are not formed; instead, excess halogen deis notable with the meso isomer having the larger value of ' J , composes the complexes with oxidation of the ligand and genalthough as pointed out in connection with the generally similar eration of [ PtCl6l2-. Attempts to prepare iridium(1V) ditellurotrends in 1J(195Pt-77Se),the coupling constant is likely to be very ethers have also failed.,, sensitive to the orientation of the free lone pair and is probably Conclusion not a reliable indicator of bond strength differences in the two The synthesis, properties and structures of the first examples invertomers. Few values for IJ( 1gsPt-'2sTe) are available for of complexes of chelating ditelluroethers have been described. comparison, but we note values of 900 H z for cis-[Pt(TeDetailed multinuclear N M R studies have revealed systematic (CH2CH2Ph)2)2C12]?8 -1553 H z for [Pt(Me2Te)C13]-,-1092 H z changes in 6('25Te) and 6(19%) with diastereoisomer, trans ligand, and metal center. Close parallels between corresponding selenoether and telluroether complexes have been observed. Gulliver, D. J.; Hope, E. G.; Levason, W.; Murray, S. G.; Marshall, G.
+
L. J . Chem. SOC.,Dalton Trans. 1985, 2185. Garrou, P. E. Chem. Rev. 1981, 81, 229. Goggin, P. L.; Goodfellow, R. J.; Haddock, S. R. J . Chem. Soc., Chem. Commun. 1975, 176. Abel, E. W.; Orrell, K. G.; Platt, A. W. G. J . Chem. Soc., Dalton Trans. 1983, 2545. Pregosin, P. S.In Phosphorus-31 NMR Spectroscopy in Stereochemical Analysis; Verkade, J. G., Quin, L. D., Eds.; VCH Publishers: Deerfield Beach, FL, 1987; Chapter 14. Gysling, H. J.; Zumbulyadis, N.; Robertson, J. A. J. Organomer. Chem. 1981, 209, C41.
(29) McFarlane, H. C. E.; McFarlane, W. J . Chem. SOC.,Dalton Trans. 1973, 2416. (30) Gulliver, D. J.; Levason, W.; Smith, K. G.; Selwocd, M. J.; Murray, S. G. J . Chem. SOC.,Dalton Trans. 1980, 1872. (31) Gulliver, D. J.; Levason, W. J. Chem. SOC.,Dalton Trans. 1982, 1895. (32) Hiraishi, J.; Nakagawa, I.; Shimanouchi, T.Spectrochim. Acta 1964, 20, 819. (33) Cipriano, R. A,; Levason, W.; Pletcher, D.; Powell, N . A,; Webster, M. J . Chem. SOC.,Dalton Trans. 1987, 1901.
696 Inorganic Chemistry, Vol. 28, No. 4, 1989
Kemmitt et al. usual Lp factor. Omitting observations with F < 3a (F)(625) left 2547 used in the analysis. The E statistics favored the centrosymmetric space group Pi,and the structure was solved by the direct methods strategy (EEES) available in SHELX." The E maps all contained multiple images of the PdBr2Tez residue, and the correct solution was established by repeated structure factor and electron density calculations. Hydrogen atoms were added in calculated positions (d(C-H) = 0.95 A) and two reflections (010; 021) thought to be suffering from extinction were removed. Full-matrix least-squares refinement minimizing Zw(lFol - IF,I)2 converged to R = 0.023 [ R , = 0.022, 182 parameters, 2545 reflections, anisotropic (Pd, Te, Br, C) thermal parameters, w = l/(a2(r;? + O.O0003P), maximum shift/error = 0.11. The final difference electron-density synthesis showed all features in the range +0.52 to -0.56 e A-'. Scattering factors for neutral atoms and anomalous dispersion corrections were taken from SHELX (Br, C, H) and ref 36 (Pd, Te), and all calculations were performed on an IBM3090 computer using the programs SHELX,35 ORTEP,37 and XANADU." The non-hydrogen atomic positions are given in Table V, and other structural parameters are available as supplementary material.
Table V. Atomic Coordinates for [Pd{PhTe(CH2)3TePhJBr2] X
Pd Te(1) Te(2) Br(1) Br(2) C(l) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15)
0.33486 (4) 0.56582 (4) 0.44843 (4) 0.09613 (6) 0.20883 (6) 0.2734 (6) 0.1744 (8) 0.0615 (9) 0.0456 (8) 0.1421 (8) 0.2582 (7) 0.6687 (6) 0.7081 (6) 0.7635 (6) 0.4503 (6) 0.5453 (7) 0.4714 (9) 0.3069 (8) 0.2122 (8) 0.2847 (7)
Y 0.36572 (3) 0.27446 (3) 0.43732 (3) 0.44383 (5) 0.29963 (5) 0.2843 (4) 0.3237 (5) 0.2286 (7) 0.0954 (7) 0.0537 (6) 0.1482 (5) 0.3786 (5) 0.2671 (5) 0.3002 (5) 0.0654 (4) -0.0198 (5) -0.1572 (5) -0.2093 (5) -0.1252 (5) 0.0139 (5)
Z
u," A2
0.83706 (4) 0.95831 (3) 0.68576 (3) 0.71578 (6) 0.97949 (6) 0.4776 (5) 0.3775 (6) 0.2402 (6) 0.2034 (6) 0.3026 (7) 0.4424 (6) 0.6923 (5) 0.7375 (5) 0.8965 (5) 0.8176 (5) 0.8429 (6) 0.7568 (7) 0.6494 (6) 0.6253 (7) 0.7105 (6)
32.2 (2) 34.7 (2) 35.5 (2) 49.7 (2) 49.1 (2) 37 (2) 62 (2) 79 (3) 70 (3) 70 (2) 59 (2) 46 (2) 43 (2) 43 (2) 37 (2) 56 (2) 63 (3) 60 (2) 69 (2) 52 (2)
Equivalent isotropic temperature factor from anisotropic atom lo3). I/ = one-third of the trace of the orthogonalized U.
Acknowledgment. We thank the S E R C for support (T.K.) and Dr. M. B. Hursthouse for the X-ray data collection on the Queen Mary College, London/SERC diffractometer. (X
Experimental Section Physical data were recorded as described p r e v i o ~ s l y . * ~ *12sT ~ ~el* HI ~~ data were recorded on a Bruker AM360 instrument at 113.6 MHz on saturated solutions in DMSO or DMF containing 5% deuteriated solvent to provide the lock and are referenced to neat external Me2Te.3 "Sel'H) spectra were recorded as described! except those for PhSe(CH,),SePh complexes, which were run in freshly prepared DMF solutions containing ca. 5 mg of [Cr(acac),] with no relaxation delay. The ligands3 and dithioether30 and di~elenoether~ complexes were made by literature methods. Representative preparations for two telluroether complexes are described. Dichloro[l,3-bis(pbenyltelluro)propane]platinum(II). The ligand (0.113 g, 0.25 mmol) was added to a rapidly stirred solution of [Pt(MeCN)2C12] (0.087 g, 0.25 mmol) in dichloromethane (25 cm') and stirred for 3 h. The precipitate was filtered off, washed with diethyl ether and dried in vacuo. Yield: 0.172 g, 96% Dibromo(2,6-ditelluraheptane)platinum(II). An excess of sodium bromide dissolved in water (5 cm3) was added to [Pt(MeCN),CI,] (0.087 g, 0.25 mmol) in acetontrile (40 cm)). The mixture was refluxed for 4 h and then allowed to cool. The ligand (0.082 g, 0.25 mmol) was added dropwise with vigorous stirring. After 3 h the precipitate was filtered off, washed with water, acetonitrile, and diethyl ether, and dried. Yield: 0.158 g, 92% X-ray Data and Structure Solution. Orange air-stable rhomb-shaped crystals were grown from diethyl ether-acetonitrile solutions. Preliminary photographic X-ray examination established the crystal system and approximate cell dimensions. Accurate cell dimensions were obtained from 25 carefully centered reflections on an Enraf-Nonius CAD-4 diffractometer equipped with Mo K a radiation. The crystals are triclinic, a = 8.968 (1) A, b = 10.978 ( 1 ) A, c = 11.070 (2) a = 108.16 6 = 113.15 (110, = 98.95 (I)o, V = 902.65 A), and mol wt of 717.7 for CISHI6Br2PdTe2.Dmcas-=2.60 (4) (flotation), Dcakc= 2.640 g for Z = 2, space group P1 (from the analysis), F(000) = 652, and p(Mo Ka) = 85.1 cm-'. A crystal at room-temperature (0.3 X 0.07 X 0.2 mm) was mounted in a thin-wall glass capillary. Data were collected with Mo Ka radiation (A = 0.71069 A) and graphite monochromator. In total, 3394 reflections were measured (1.5O < 0 < 25O; h (0 to lo), k (-13 to +13), I(-13 to +13)), and after averaging (Rint= 0.012), there remained 3172 unique reflections. No decay was observed in the measured check reflections and an empirical $-scan absorption correction was applied to the data (transmission: maximum, 100.0%; minimum 60.0%) together with the
a,
(w,
(34) Hope, E. G.; Levason, W.; Powell, N. A. Inorg. Chim. Acta 1985, 115, 187. (35) Sheldrick, G. M . 'SHELX Program for Crystal Structure Determination"; University Chemical Laboratory: Cambridge, England, 1976.
Registry No. meso-[Pd(MeTe(CH,),TeMe)CI,],118376-9 1-3; meso- [Pd(MeTe(CH2)3TeMe)Br2],1 18376-92-4; meso-[Pd(MeTe(CH2),TeMe)12], 118376-93-5; meso-[Pd(PhTe(CH2),TePh)C12], 11 8376-94-6; meso-[Pd(PhTe(CH,),TePh)Br,],118376-95-7; meso[Pd(PhTe(CH2)3TePh)12], 1 18376-96-8; meso- [Pt(MeTe(CH2),TeMe)C12], 118376-97-9; meso-[Pt(MeTe(CH,),TeMe)Br,], 118376-98-0; mes0-[Pt(MeTe(CH~)~TeMe)1,], 118376-99-1; meso[Pt(PhTe(CH2)3TePh)Clz],1 18377-00-7; meso- [Pt(PhTe(CH2)3TePh)Br,], 118377-01-8; meso-[Pt(PhTe(CH2)3TePh)12], 118377-02-9; [Pd(MeCN),Cl2], 14592-56-4; [Pd(MeCN),Br,], 53623-19-1; [Pd(MeCN),12], 118377-03-0; [Pt(MeCN),CI,], 13869-38-0; [Pt(MeCN),Br2], 13869-36-8; [Pt(MeCN),12], 118377-04-1; dl-[Pd(MeTe(CH2)3TeMe)C12],1 18455-52-0; dI-[Pd(MeTe(CH2)3TeMe)Br2], 1 18455-53- 1 ; ~fl-[Pd(MeTe(cH~)~TeMe)I~], 118455-54-2; dl-[Pd(PhTe(CH2)3TePh)Clz],118455-55-3; dl-[Pd(PhTe(CH2)3TePh)Br2], 118455-56-4; dl-[Pd(PhTe(CH,)3TePh)12], 118455-57-5; dl-[Pt(MeTe(CH,),TeMe)CI,], 118455-58-6; dI-[Pt(MeTe(CH2)3TeMe)Br2], 118455-59-7; dl-[Pt(MeTe(CH2),TeMe)12], 118455-60-0; dl-[Pt(PhTe118455(CH2),TePh)C12], 118455-61-1; dI-[Pt(PhTe(CH2)3TePh)Br2], 62-2; dl-[Pt(PhTe(CH2),TePh)12], 118455-63-3; dl-[Pt(MeSe(CH,),SeMe)Cl2], 98931-78-3; dl-[Pt(MeSe(CH2)3SeMe)Br2], 989125 1-7; dl-[Pt(MeSe(CH,),SeMe)I,], 9893 1-79-4; dl-[Pt(PhSe(CH2),SePh)Cl2], 118455-64-4; dI-[Pt(PhSe(CH2)3SePh)Br2], 11845565-5; dl- [Pt(PhSe(CH2),SePh)12J, 118377-05-2; meso-[Pt(MeSe(CH2),SeMe)C1,], 99397-10-1; meso-[Pt(MeSe(CH2),SeMe)Br2], 99397-09-8; meso-[Pt(MeSe(CH2)3SeMe)Iz], 99397-08-7; meso-[Pt(PhSe(CHz)3SePh)C12],1 18455-66-6; meso- [Pt(PhSe(CH2)3SePh)Br2], 11 8455-67-7; meso-[Pt(PhSe(CH2)3SePh)12], 118455-68-8; meso-[Pt(MeS(CH2),SMe)CI2], 84026-96-0; ~ ~ ~ O - [ P ~ ( M ~ S ( C H ~ ) ~ S M ~ ) B ~ , ] , 104975-51- 1; meso-[Pt(MeS(CH2),SMe)12], 118455-69-9; meso- [Pt(PhS(CH2),SPh)CI2], 118455-70-2; ~~~O-[P~(P~S(CH~)~SP~)B~,], 118455-71-3; meso-[Pt(PhS(CH2)3SPh)12], 118455-72-4; dl-[Pt(MeS(CH,),SMe)CI,], 7 1499-16-6; dl-[Pt(MeS(CH2),SMe)Br2], 1049755 5 - 5 ; dl-[Pt(MeS(CH2),SMe)12], 118455-73-5; dl-[Pt(PhS(CH,),SPh)CI,], 118455-74-6; dl-[Pt(PhS(CH,),SPh)Br,], 118455-75-7; 125Te,14390-73-9; 195Pt,14191-88-9; 77Se, 14681-72-2; chlorine, 778250-5.
Supplementary Material Available: Tables of anisotropic thermal parameters, calculated H atom coordinates, and full bond length and angle data (Tables S-14-3) (3 pages); a table of calculated and observed structure factors (Table S-4) (7 pages). Ordering information is given on any current masthead page.
(36) International Tablesfor X-ray Crysfallography; Kynoch : Birmingham, England, 1974; Vol. IV. (37) Johnson, C. K. Oak Ridge Nafl. Lab., [Rep.] ORNL (US.)1965, ORNI.-3794. - - ._- . . (38) Roberts, P.; Sheldrick, G. M. 'XANADU Program for Crystallographic Calculations";University Chemical Laboratory: Cambridge, England, 1979.
